Press with enclosed toggles



1959 I... L. HARPER 2,897,784

PRESS WITH ENCLOSED TOGGLES Filed March 25, 1957 3 Sheets-Sheet.- 1

INVENTOR.

Zea/2am [.f/arper flziorweu Aug. 4, 1959 L. L. HARPER 2,897,784

PRESS WITH EN CLOSED TOGGLES Filed March 25, 1957 FIG: 5

s Sheets-She'c 2 INVENTOR.

- Leona/a Lfiarper United States Patent PRESS WITH ENCLOSED TOGGLES Leonard L. Harper, Niles, Ill., assignor to Crane Packing Company, Morton Grove, 111., a corporation of Illinois Application March 25, 1957, Serial No. 648,024 14 Claims. (Cl. 121-38) The present invention relates to a press, and more particularly to a press with piston force multiplier.

In general, the device of the invention is a press including a cylinder with a piston working therein and a ram or plunger extending therefrom for engaging the work piece to be worked on, and adapted to actuation by a suitable motive power, such as compressed air.

A broad object of the invention is to provide a device or the general character disclosed including novel construction for multiplying the force imposed by the piston so as to produce increased thrust on the ram.

Another object is to provide a press having force multiplying means of the kind stated, in which the maximum increase in thrust on the ram occurs adjacent the end of the power stroke of the ram, whereby the device can be effectively used on work pieces which require imposition of maximum pressure only adjacent the end of the power stroke, and which consequently is more economical than presses of uniform pressure of the maximum capacity required.

A further object is to provide a press of the foregoing general character which is extremely small and compact.

Still another object is to provide a press having force multiplying means of the general character stated, in which the force multiplying means includes novel linkage interconnected between the piston and ram and arranged in a novel compact manner with respect to its mounting on the fixed cylinder of the device for receiving the reaction to the thrust of the ram.

Another object is to provide a press of the general character noted, in which the linkage is arranged in perfectly balanced condition whereby the ram can be perfectly indexed and maintained in perfect alignment throughout its power stroke.

A further object is to provide a press of the general character stated, which includes a cylinder or housing that entirely encloses the moving parts except an extended end portion of the ram, whereby a quantity of oil may be constantly maintained in the cylinder for immersing a portion of the moving parts and effectively lubricating all of them.

Another object is to provide a press of the foregoing general character that, because of the extreme multiplication of force effected therein, is particularly well adapted to operation by compressed air, and which consumes substantially less compressed air than presses heretofore in use, and further in which air bounce is entirely eliminated and good holding power is established.

Other objects and advantages of the invention will appear from the following detail description taken in conjunction with the accompanying drawings in which Fig. 1 is a side view, partially in elevation and partially in section, of a press, and mounting means therefor, embodying the principles of the invention;

Fig. 2 is a view, partially in elevation and partially in section, of the press of Fig. 1 in projected or extended position;

Fig. 3 is a sectional view taken on line 3-3 of Fig. 2;

Fig. 4 is a sectional view taken on line 44 of Fig. 2;

Fig. 5 is a view partially in elevation and partially in section, of a press similar to that of Figs. 1 and 2, but slightly modified relative thereto; v

Fig. 6 is a vertical sectional view of another modified form of press;

Fig. 7 is a vertical sectional view of a further modified form of press; and

Fig. 8 is a vertical view of still another modified form of press.

Referring in detail to the drawings, attention is first directed to Figs. 1 to 4, inclusive, illustrating a preferred form of the invention. In Fig. 1 a press made according to the present invention is shown in its entirety at 12, mounted on a suitable stand 14 which includes a base 16 and a mounting adapter 18 in the form of an upright mounted on the base. On the upper end of the mounting adapter 18 is a mounting plate 20 of suitable construction for supporting the press 12 by suitable means the details of which do not enter into the present in-' vention and need not be described herein. The press, as will be observed, is supported directly over a portion of the base 16 on which is mounted an anvil 22 for cooperation with the ram of the press in a manner that is well known. The press 12 includes a cylinder 24 constituted by two main parts, namely, an upper portion 26 and a lower portion 28. The upper portion 26 is generally in theform of an inverted cup, and has an end wall 30 which in the normal position of the device is at the upper end, and a surrounding cylindrical wall 32. The lower part 28 serves as a closure member for the upper part 32 and includes an upper portion 34 suitably connected to the Wall 32 as by a screw connection. This part also in cludes a lower, reduced diameter portion 36 in which is V secured a tubular bearing element 38 mounted in place in a suitable manner. This bearing element 38, aswill be noted, is of substantial length so as to aid in main; taining alignment of the ram, as will be described more fully hereinbelow. The cylinder 26 defines a chamber 40, formed chiefly by the upper cup-shape member 26, and the bearing member 38 defines a bearing opening 42 which at least partially forms a continuation of the chamber 40. The internal operating mechanism of the press includes a piston indicated generally at 44 and a ram indicated generally at 46. The piston 44 is operable in the cham ber 40, having sealing and guiding engagement with the interior surface of the cylnider wall 32, while the ram 46 is reciprocable in the bearing member 38, and similarly has sealing and guiding engagement with the inner surface 42 of the bearing member. The piston and'ram are co-axial, but of different diameters as will beobserved from the drawings, and more particularly as described hereinbelow. I

Extending downwardly from the top end wall 30, is a post 48, secured thereto by suitable means such as a screw 50 (Fig. 2). This post extends centrally of the chamber 40 and to an appreciable extent axially therein. The piston 44 is of annular shape, surrounding the post 48 and reciprocable between limit positions adjacent the top and bottom, respectively, of the chamber 40. In its uppermost position it substantially engages the end wall 30, suitable gasket means '52 being interposed therebetween if desired. The portion 34 of the lower part of the cylinder forms a shoulder 54 and the piston in its lowkets 56 are interposed between the'piston and the c'yliirder wall 32 and post 48 to form oil-tight and air-tight Patented Aug. 4, 1959 seals between the elements concerned. Also, if desired, a wear ring 58 may be provided on the cylinder. It will be observed that the piston has substantial engagement inaxial direction with the cylinder wall 32 for'accurate guidingof the piston in its reciprocating movements.

The ram 46 is of. substantially lesser diameter than the piston 44 and may be of a diameter similar to that of the post 48. The ram reciprocates in the bearing member 38 with its inner or upper end extending into thechamber 40 and its outer or lower end projecting to the exterior. In accordance with known manner of construction, the lower end of the ram may be provided with adjustment means indicated generally at 60. Suitable gasket means 62 is provided between the ram and surface of the bearing member 38 toprovide oil-tight and airtight seal therebetween. This seal is positioned sufiicient- 1y: high in the bearing member 38 that that portion of the ram 46 which engages the seal is never exposed to the exterior when the ram is in its lowermost projected position.

The cylinder 24 is provided with an oil fill hole and plug 63 for introducing oil into the chamber 40. The cylinder is sealed against the escape of oil whereby to retain a quantity of oil in the chamber to the end of effectively lubricating all of the moving parts therein.

Force multiplying means is provided between the piston and ram for multiplying the force imposed on the ram by the piston. This force multiplying means assumes the form of the toggle joint or linkage indicated generally at 64. This toggle joint is contained entirely within the cylinder and includes two or more portions or parts disposed uniformly about the central 1ongitudinal axis of the cylinder which passes through the piston and ram. Where two portions or parts are used as shown in the drawings, they are disposed on opposite sides of a plane perpendicular to the paper through that axis, as viewed inFigs. 1 and 2. Each part includes a toggle joint made up of a pair of struts 66 and 68 and a link 70. The struts 66 and 68 are pivoted respectively to the lower end of the post 48 and the upper end of the ram 46, and are pivotally connected together at their other ends to form an elbow, and the link 70' is pivoted at one end to the struts at the elbow, while its other end is pivoted to the piston 44. Each of these members of the joint, namely the struts and the link, may be made up of a plurality of elements in accordance with the construction illustrated in Fig. 5 and described below, for the purpose of symmetrically distributing the forces involved. However, the toggle joint may be considered as including the members mentioned, namely the two struts and the link, for the purpose of describing the forces involved as between the piston and the ram.

The toggle joint, and the other parts and elements, are so arranged in dimensions and proportions that when the piston 44 is in its uppermost position, the ram 46 is in its uppermost position illustrated, being spaced from the post 48 a small distance. Upon downward movement of the piston, from an assumed starting position as that just referred to, by a suitable force as compressed air, as described below, the downward thrust of the piston is imparted to the links 70 and transmitted by the links 70 to the struts-66 and 68. These struts consequently tend to move toward a straight line between the axes of the pivotal connections between the struts and the post 48 and the ram 46. This forces the ram downward, as will be understood, and the. movement continues to the fully projected position of Fig. 2, in which the piston 44 is in engagement with the fixed shoulder 54.

Upon reverse or upward movement of the piston by suitable means such as compressed air, the thrust of the piston is again imparted to the links 70 and transmitted by the links to the struts 66 and 68. This thrust tends to pull the interconnected ends of the respective struts 66 and 68 to the transverse position of Fig. 1, which movement consequently draws upwardly on the ram 46.

This movement continues until the piston engages the upper end wall 30, through the medium of the gasket 52, and is brought to an abrupt stop.

In the starting position as represented in Fig. 1, the links 70 are in a position closely approximating the vertical, or perpendicular to the line interconnecting the axes of connection between the links and the struts on opposite sides of the device. In the projected position as represented in Fig. 2, the respective struts 66 and 68 are in a maximum straightened position, while the links 70 are closely adjacent the horizontal or a line interconnecting the axes of connection between the links and the struts on opposite sides of the device.

As noted above, the struts 66 and 68 and the links 70 may be composed of a plurality of elements, arranged as illustrated in Fig. 5. Each of these members includes a pair of elements indicated by the same reference numerals with the sub-scripts a and b, respectively. The pair of elements making up each of the members are disposed symmetrically on opposite sides of a plane perpendicular to the axes of pivotal connection between those members so as to accurately balance the forces involved. The lower end of the post 48 and the upper end of the ram 46 may be shaped to provide cut-way portions and central projections 72 and 74, respectively, for providing the desired pivotal supporting means for the struts 66 and 68. Similarly, the piston may be provided with cut-away portions 76 for pivotally mounting the links 70.

The device is well adapted to actuation by compressed air. Compressed air is an economical and convenientsource of power for many uses, and it is commonly provided at many work stations in a manufacturing plant. Accordingly, the device of the present invention may be utilized for the many purposes for which it is useful with a minimum of adaptation or modification of presently existing equipmen. Furthermore, because of the great multiplication of power provided by the device, compressed air may economically be used for providing the intense pressures involved, where it could not be so economically used heretofore. The means and specific elements for controlling the compressed air to the press are standard or conventional and need not be described in detaiL. A source air line 78 conducts the compressed air to a suitable and known reversing valve 80 from which an air line 82 leads to the press above the piston and an air line 84 leads to the press below the piston. An exhaust mufller 86 may be provided for receiving the air exhausted from the reversing valve 80. Other appurtenances and controls may be provided as desired. In operation of the device, the operator first sets the valve80 for admitting air through the line 82 to the chamber above the piston. This same setting provides for an opening from the line 84 tov the exhaust mufller 86. The compressed air admitted above the piston drives the piston. and ram downwardly. The operator then reverses the valve 80 and admits air through the line 84 to the. chamber below the piston which raises the piston and ram, and the valve in the latter setting provides an opening from the air line 82 to the exhaust mufiler 86. It will be understood that the control of the valve 80 may bev manual or automatic, as desired.

In further description of the operation of the press, it is pointed out that the ratio of movement between the piston and ram, in the initial stages of the power stroke. is low, i.e., the ram moves at a much greater rate than the piston. Throughout the power stroke, however, the rate of movement of the ram continually lessens relative to any given rate of movement of the piston 44. In the final portion of the power stroke, the movement of the piston 44 is great, while the movement of the ram is small, with consequent great multiplication of force from the piston to the ram, as will be understood from the. action of the toggle joint. Air bounce is entirelyelimi ma ed- As an example of the great multiplication of forces.

involved,air pressure on the order of one hundred pounds p.s.i. provides, for example, 1200 pounds pressure on the piston, the piston being appropriately dimensioned to that effect. The pressure provided by the ram, in response to this force imposed on the piston, increases greatly to the end of thepower stroke and at the last increment, the pressure is on the order of 16,000 pounds.

Because of the great increase in pressureproduced by the ram at the end of its stroke, the press has been found particularly useful in certain kinds of work such, for example, as compressing powdered plastic, etc. In the initial stages of compression of such material, a large portion of the pressure involved may be utilized only for driving air from between the particles, and the intense pressures ultimately required for compacting the particles are required only at the final stages of compression. vention, the tremendous increase in compression provided is extremely effective in compressing materials of the character noted, and specimens of such material compressed with a device made according to the present invention has been found on analysis to be as perfect as similar specimens formed by a press of uniform pressure. Other materials for which the press has been found effective, are medical tablets, powdered metals, and concrete flooring blocks. The press is also effective for such operations as coining and crimping, shallow shearing, etc.

The press is extremely comp-act and small, and such a press capable of providing the intense pressures mentioned above,'narnely, 16,000 pounds, can be easily picked up and handled by the hand.

In 'the use of the device of the present in- Fig. 5 shows a form of press generally like the press of Figs. 1 to 4 described above, but modified to include spring means for returning the piston to retracted position. In Fig. 5, spring means 90 in the form.- of coiled compression springs, are interposed between the piston 44 and a lower part 28 of the cylinder, the latter part forming a fixed portion of the cylinder. The springs 90 have their ends received in recesses 92 in the part 28 and recesses 94 in the piston, to enable the springs to compress sufliciently to permitthe piston to engage the shoulder 54. In other respects, the device of Fig. 5 is essentially similar to the device of Figs. 1 to 4. The spring means 90 work to the end of economy, in eliminating the use of compressed air for returning the piston and ram in retracting direction.

The toggle joint, it will be observed, is perfectly balanced and symmetrical in all directions whereby to maintain perfect accuracy in the critical portions of the press. The ram may be accurately indexed with respect to a work piece on the anvil 22, in retracted position, and such accuracy of indexing will be maintained throughout the power stroke. The positive limits of movement of the piston, and hence the ram, also provides for greater accuracy in indexing the ram, and particularly the engagement of the piston with the shoulder 54 which determines the limit of movement of the ram in compressing direction. The positive stop provided by the shoulder 54 assures perfect indexing and compression effect on the work piece being worked on.

Figs. 6, 7 and 8 show modified forms of press, utilizing a toggle joint in position reversed from that shown in Figs. 1 to 5 and described above. In Figs. 1 to 5 the struts of the toggle joint are connected to the ram and a fixed portion of the cylinder or housing at the longitudinal central axis of the device. In the forms of Figs. 6 to 8 this connection is at the periphery or marginal portion of the cylinder. In a complementary manner, in Figs. 1 to 5, the links are connected with the piston at the periphery of the latter, while in Figs. 6 to 8, they are connectedwith the piston at the longitudinal central Referring first to the'form of'Fig. 6, the device indi respects to the respective elements 36 and .38 of Fig. 1. v

The cylindrical walls 106 and 108 have mating flanges 114 and 116 for securing the pants together by suitable means such as screws 118, and when the two cylinder or housing parts are so secured together they form the completed cylinder defining a chamber 120. The ram, indicated in this case at 122, is generally of a diameter similar to that of the ram described above but is provided with an enlarged head 124 secured to the ram proper by suitable means such as a screw 126. The head has bearing and guiding engagement with the inner surface of the cylindrical wall 108 and on its upper surface is provided with a cut-away portion defining an upwardly extending projection 128 for pivotally securing the struts of the toggle joint utilized for multiplying the force imposed on the ram. The toggle joint or linkage is indicated in its entirety at 130 and includes like parts disposed on opposite sides of the longitudinal central axis of the device, similarly to that described above. The toggle joint includes struts .132 and 134, in each part, and a link 136 also in each part. The struts 132 and 134 are pivotally connected to the respective members in a zone adjacent the periphery of the chamber 120. For conneoting the struts to a fixed portion of the cylinder or housing, a ring 138 is provided having a peripheral rib 140 gripped between insert portions in the flanges 114 and 116, forming a peripheral recess 142, the rib, and hence the ring, being clamped between the flanges 114 and 116. The struts 132 are pivoted in the ring 138 while the struts 134 are pivoted on the head 124 of the ram. The struts are pivoted together at their opposite ends, forming an elbow and the links 136 are pivoted at one end to the struts at the elbows, and at their other end to the piston, which in this case designated 144. The piston 144, in the present instance, has a head portion 146 having sealing and guiding engagement with the wall 106 and a central axially elongated and reduced post-like portion 148 extending downwardly and into the ring 138. The ring is of sufiiciently great axial dimension or thickness, to receive the portion 148 of the piston throughout the full range of reciprocation of the piston, for guiding the latter.

The struts 132 and 134 are connected to the respective members on which they are mounted in a zone adjacent the periphery of the chamber which is sufficient to receive the struts, or respective portions of the struts, in all positions of the struts and piston. When the piston is in its lowermost position, the portion 148 thereof is driven down to a position between the upper ends of the opposite struts .132, but in such position the struts are straightened sufiiciently to receive the port-ion 148 of the piston therebetween.

The operation of the device of the present embodiment is believed clear, in view of the description of the embodiments of Figs. 1 to 5. Briefly, the compressed air is introduced through an opening 150 for driving the piston in projecting direction, or in the power stroke, while the compressed air is introduced through an opening 152 below the piston, for retracting the piston, under control of suitable valve means such as the reversing valve 80 of Fig. 1.

The embodiment of the invention illustrated in Fig. 7 is similar to that of Fig. 6 with the exception that the piston 154 of the present device includes a head portion 156 which is of greatly increased mass and consequent 7 increased inertia. The piston of the present embodiment may be utilized where greater impact power is desired, particularly in an early portion of the power stroke. The piston may be driven or fir-ed" at a rapid rate and the great mass and inertia of the piston provide the increased power desired for the initial impulse required in such operations as blanking and notching. The greatly increased force at the terminal portion of the power stroke, as in the previous embodiments, is nevertheless retained. The arrangement of the toggle joint in which the respective elements are connected to the fixed cylinder at the periphery and to the piston at the longitudinal central axis, enables the use of a solid piston, i.e., transversely'continuous, having consequently much greater mass and inertia, as compared with an annular piston.

Fig. 8 illustrates a still further embodiment of the invention and includes a double piston head for increased area and consequent increased force provided by the piston. In the present instance, the piston indicated at 158 includes two heads, 160 and 162, interconnected to function as a single piston. The piston is reciprocable in. a cylinder or housing 164 which is made up of two parts, namely, a lower part 166 and an upper part 168, detachably and suitably secured together as by a threaded connection. Interposed between these parts is a transverse Wall or partition 170 dividing the interior of the cylinder into two chambers 172 and 174 in which the heads 162 and 160, respectively, reciprocate. The heads are connected by a bolt or stem 176 having a headed portion 178 secured in the lower piston head 162 by suitable means such as a ring 180 engaging the piston head and threaded in a recess in the head. The stem 176 extends through a central aperture in the wall or partition 170 and is secured to the upper head 160 by suitable means such as a screw threaded connection. The chambers 172 and 174 are thus isolated from each other, and airtight to the exterior, except through the openings for delivering air to the chambers and exhausting it therefrom. I

In the operation of the device compressed air is introduced through openings 182 and 184 into the respective chambers 174 and 17 2 above the piston heads, which operates to drive the piston downwardly. The opening 182 may be in [the top wall or end wall of the cylinder while the opening 184 passes through the transverse wall or partition 170. For retracting the piston, compressed air is introduced through another opening 186, which, for convenience, is formed in the transverse wall or partition 170, and opens into the chamber 174 below the upper piston head 160.

The lower piston head 162 is similar in all material respects to the piston of Fig. 6 and the force multiplying means interconnecting the piston and the ram is the same as that illustrated and described in connection with Figs. 6 and 7.

In the present instance, greatly increased force can be applied to the piston for any given air pressure, as will be understood from the increased aggregate area of the piston portions. It will be understood that this arrangement is not limited to two heads of the piston, but may comprise any desired and practical number.

While I have disclosed herein certain preferred embodiments of the invention, it will be understood that changes may be made within the scope of the appended claims.

I claim:

1. A device of the character disclosed comprising a cylinder defining a chamber, a piston reciprocable in the chamber and entirely enclosed therein by the cylinder, a ram reciprocable in the cylinder in coaxial alignment with the piston and having a portion in the chamber and a portion extending through an opening in the cylinder to the exterior, force multiplying means in the cylinder interconnected between the piston and ram and a fixed portion 'of the cylinder operative for mul iplying the force. imposed on the. ram by thepiston in one direc tion of movement of; the piston and; ram, and, means for imposingforce' onone side of the piston efifective for moving the piston and ram in the said one direction.

2. A device 'of the character disclosed comprising a cylinder defining a, chamber, a piston reciprocable in the chamber and entirely enclosed, therein by the cylinder, a ram reciprocable in the cylinder in coaxial alignment with the piston and having a portion in, the chamber and a portion extending through an opening in the cylinder to the exterior, toggle joint means in the cylinder interconnected between the piston and ram and a fixed portion of the cylinder operative for multiplying the force imposed on the ram by the piston in one direction of movement of the piston and ram, and means for imposing force on one side of the piston effective for moving the piston and ram. in the said one direction.

3. A press comprising a cylinder defining a chamber including a piston portion and a ram portion opening to the exterior, a piston reciprocable in the piston portion of the chamber and a ram reciprocable in the ram portion in coaxial alignment with the piston and having a portion extending to the exterior, positive stop means,

limiting the movement of the piston at opposite ends of a predetermined range, toggle joint means in the cham ber interconnected between the piston and ram and a fixed portion of the cylinder and effective for multiplying the force imposed on the ram by the piston in one direction of movement of the piston and ram, said ram having bearing and guiding engagement with the cylinder throughout an extent substantially equivalent to the range of reciprocating movement of the ram, and means for imposing force on one side of the piston effective for moving the piston and ram in the said one direction.

4. A press comprising a cylinder defining a chamber including a piston portion and a ram portion opening to the exterior, a piston reciprocable in the piston portion of the chamber and a ram reciprocable in the ram portion in coaxial alignment with the piston and having a portion extending to the exterior, positive stop means limiting the movement of the piston at opposite ends of a predetermined range, toggle joint means in the cylinder interconnected between the piston and ram and a fixed portion of the cylinder and effective for multiplying the force imposed on the ram by the piston in one direction of movement of the piston and ram, oil seal means between the ram and cylinder, said ram having guiding engagement with the cylinder throughout an extent substantially equivalent to the range of reciprocating movement of the ram at a position outwardly of the oil seal means, a quantity of lubricant confined in the chamber between the piston and ram, the piston, toggle joint means, ram, and lubricant constituting a self-contained assemblage enclosed entirely within the cylinder except an end portion of the ram, the cylinder being capable of sealingly containing the lubricant therein, and means for imposing force on one side of the piston effective for moving the piston and ram in the said one direction.

5. A press comprising a cylinder having a surrounding Wall defining a chamber and having a post extending from an end wall into the chamber, the cylinder having means including a bearing defining an opening from the chamber to the exterior coaxial with the post, an annular piston surrounding the post and reciprocable in the chamber, means sealing the piston to the surrounding wall and post, a ram reciprocable in the bearing and having a portion projecting to the exterior, toggle joint means including struts pivoted respectively to the post and ram and pivoted together to form an elbow, a link pivoted to the struts at the elbow and to the piston, a

quantity of lubricant in the cylinder, the piston, toggle joint means, and ram, with the lubricant, constituting a self-contained unit enclosed entirely within the cylinder except an end portion of the ram, the cylinder being effective for sealingly containing the lubricant therein, and means for imposing force on one side of the piston effective for moving the piston and ram in a direction to' cause the ram to project progressively to the exterior of the chamber.

6. A press comprising a cylinder having a surrounding wall defining a chamber and having a post extending from an end wall into the chamber, the cylinder having means including a bearing defining an opening from the chamber to the exterior coaxial with the post, an annular piston surrounding the post and reciprocable in the chamber, means sealing the piston to the surrounding wall and post, a ram reciprocable in the bearing and having a portion projecting to the exterior, toggle joint means including symmetrical halves on opposite sides of the longitudinal central axis through the piston and ram, each half including struts pivoted respectively to the post and ram and pivoted together to form an elbow, a link pivoted to the struts at the elbow and to the piston, a quantity of lubricant in the cylinder, the piston, toggle joint means, and ram, with the lubricant, constituting a self-contained assemblage enclosed entirely within the cylinder except an end portion of the ram, the cylinder being capable of sealingly containing the lubricant therein, and means for imposing force on one side of the piston elfective for moving the piston and ram in a direction to cause the ram to project progressively through the bearing to the exterior of the cylinder.

7. A device of the character disclosed comprising a cylinder defining a chamber and having a surrounding wall and an end wall, a post extending from the end wall into the chamber, the cylinder having bearing means defining an opening coaxial with the post and leading from the chamber to the exterior and defining a limit stop surrounding the opening, an annular piston surrounding the post and reciprocable in the chamber between a retracted position and a projected position in which its forward end engages said limit stop, a ram reciprocable in said hearing means between a retracted position in which an inner end thereof is closely adjacent the post and an outer end thereof projects to the exterior and a projected position in which it is moved away from the post and further projected to the exterior, toggle joint means including symmetrical halves on opposite sides of the longitudinal central axis of the piston and ram, each half including struts pivoted respectively on the post and ram and pivoted together to form an elbow, and a link pivoted to the struts at the elbow and to the piston, the struts and links each being made up of a plurality of elements spaced along the pivot axes thereof, the strut and link elements being so relatively positioned along said pivot axes as to maintain balance about a longitudinal central plane perpendicular to those axes, said struts and links being inset in the respective post, ram and piston so as to enable the ram to closely approach the post and the piston to engage said limit stop when the ram and piston are in the respective ones of their said positions, said links being in a position closely adjacent a position parallel with said longitudinal central axis when the piston is in retracted position, and in a position closely adjacent a line perpendicular to said longitudinal central axis when the piston is in projected position, and means for imposing force on one side of the piston elfective for moving the piston and ram in the direction to project the ram to the exterior as aforesaid.

8. The construction of claim 7 in which the elements of the struts of each said half of the toggle joint means are respectively alternately arranged, and the elements of the links are disposed outwardly of the elements of the struts.

9. A press comprising cylinder means defining a chamber including a relatively large diameter portion and a relatively small diameter portion leading from the large diameter portion to the exterior, a piston reciprocable in the large diameter portion and a ram reciprocable in the small diameter port-ion, force multiplying means interconnecting the piston and ram for multiplying the force imposed on the ram by the piston in one direction of movement of the piston and ram, a quantity of lubricant in the cylinder, the piston, force multiplying means, and ram, with the lubricant, constituting a self-contained assemblage enclosed entirely Within the cylinder except an end portion of the ram, the cylinder being capable of sealingly containing the lubricant therein, means for imposing compressed air selectively on opposite sides of the piston for moving the piston and ram in corresponding direction, and a post extending from an end wall, said piston being annular in form and surrounding the post and being of substantially greater transverse area than the ram, and the force multiplying means being connected between the post and piston.

10. The construction of claim 5 in which the means defining said opening forms a limit stop for engagement by the piston, and spring means is included for moving the piston in a retracting direction which is opposite the force applying direction, the spring means being interposed between the piston and means forming the limit stop and having its ends disposed in recesses in those elements to enable the piston to engage the limit stop.

11. A press comprising a housing defining a chamber and having a cylindrical wall and means including a bearing defining a reduced diameter opening leading to the exterior, a ram reciprocable in said bearing and having a portion projecting to the exterior and an enlarged head guidingly engaging the cylindrical wall, a piston reciprocable in the chamber in the end portion opposite the ram and having a head portion guidingly engaging the cylindrical wall and a reduced portion extending toward the ram, annular supporting means secured to the interior of the cylindrical wall, toggle joint means for transmitting and multiplying force from the piston to the ram including struts pivoted at their ends respectively to the supporting means and ram head and pivoted together to form an elbow, and links pivoted to the struts at the struts at the elbow and to the reduced portion of the piston, the struts being connected to the supporting means in the annular zone outwardly of the reduced portion of the piston and positioned entirely in that zone when the ram is moved to a projected position away from the mounting means and the stnuts are extended, said mounting means serving as a guiding means for the reduced portion of the piston, and means for imposing force selectively on opposite sides of the piston effective for moving the piston in corresponding directions.

12. The construction of claim 11 in which the mounting means serves as positive limit stop means for the piston in one direction and for the ram in the opposite direction.

13. The construction of claim 11 in which the housing is made of separable parts and the mounting means is a ring clamped between interfacing surfaces of the housing ants. p 14. The construction of claim 1 in which the piston is continuous in transverse and axial directions and of substantial mass to provide added inertia to force imposed on the ram by the piston.

References Cited in the file of this patent UNITED STATES PATENTS 1,044,617 Wray Nov. 19, 1912 1,231,257 Herr June 26, 1917 2,026,347 Johnson Dec. 31, 1935 2,255,568 Page Sept. 9, 1941 2,383,082 Rossmann Aug. 21, 1945 2,743,703 Miller May 1, 1956 

